Naive users are more likely to report adverse psychological effects such as anxiety or paranoia from a single dose. In considering the potential effects of cannabis on an individual, the experience of the user must be taken into account, due to the effects of tolerance and learned behaviour. A dose of cannabis which could cause intense intoxication in a na"ve user may have little or no effect in a regular cannabis user. On the other hand, the effects of cannabis can be quite subtle, and na"ve users may not experience an effect until they have learned to appreciate it, or how to inhale the drug effectively, a situation known as "reverse tolerance".

Animal Studies

Many researchers have investigated the effects of drugs on sexual behaviour in laboratory animals, either as the main purpose of a study or as variables in studies addressing other matters.

Rodrigues de Fonseca et al noted changes in density of cannabinoid receptors in the rat hypothalamus over the oestrus cycle, with lower densities during the fertile period and suggested "possible sex steroid-dependent differences in the sensitivity of certain neuronal processes to cannabinoid treatment." Navarro et al reported "acute THC markedly altered the behavioral pattern executed by the animals in a socio-sexual approach behavior test... presumably indicating loss of sexual motivation", however Shrenker et al found neonatal THC exposure to increase adult sexual responses in mice, although the same team had earlier found THC to suppress male copulatory behaviour in rats, Uyeno reported changes in male rat sexual dominance behaviour, and Cutler et al reported cannabis to decrease sexual behaviour in mice.

In a study of hashish and mating behaviour in mice, Frischknechtet al found chronically-treated animals showed decreased sexual behaviour, and concluded "whereas tolerance to the sedative effects of hashish developed very rapidly, the drug influences on social behavior were stable". In hamsters, Turley et al found THC to stimulate female sexual receptivity behaviour (lordosis, ultrasound verbalisations). Sieber et al studying male mice, reported "sexual behavior was even more frequent in drugged animals than in controls", although they had earlier reported "sexual and aggressive behavior was not significantly affected by the drug". Dalterio et al found in-vitro THC to depress testosterone secretion from mouse testis. Frischknecht et al found hashish extract to abolish or reduce submissive behaviour by mice introduced to a previously dominant agressive animal.

In primates, Rozenkranz et al reported cannabis and THC to reduce secretion of female sex hormones (FSH,LH,Prolactin), and Smith et al counselled "it is not known how much disruption of reproductive hormone levels is necessary for changes in human fertility and sexual function to occur."

Human Studies

Due to restrictions on the availability of cannabis preparations for research purposes, there are few human studies of cannabis and sexual function in the scientific literature.

In a critical review of the effects of marijuana on sexual function, Abel stated "Marihuana usage is associated with a life-style that involves earlier and more frequent sexual activity." but commented "there is no evidence that human marihuana users... are less fertile", and criticised the rigour of animal studies "in virtually every study conducted with animals, there has been a basic confounding between direct drug action and secondary effects resulting from drug-induced decreases in food and water consumption and attendant weight loss."

Crockett et al found low dose, high dose and placebo subjects not to differ significantly in subjective ratings of sexual content of a series of test cards. Mattes et al reported a dose-dependent reduced salivary flow in human volunteers, but no direct effect on taste function. Whether cannabis may affect vaginal secretions is unclear.

In recent IDMU surveys, several respondents have listed "sex" or enhancement of sexual/sensual pleasure, as a reason for using cannabis, a positive benefit arising from cannabis use, or as their best drug experience. Quotes included "feel bliss out buzz erotic love play" and "it seems to grow my ears, eyes and heart/brain". A previous survey of 600 cannabis users in 1984 found no difference in levels of cannabis use between singles, couples, separated or gay respondents, although separated respondents did report a greater number of drug-related problems.

Summary

Although cannabis use was widely-perceived as an attribute of the permissive lifestyle in the 1960s, there appears nothing in the drug itself which would primarily stimulate sexual behaviour. With some exceptions, most animal studies suggest THC to depress the frequency of sexual activity. A number of users report improved sexual experience, attributed to the "pleasurable" perceptual changes of tactile stimuli rendering the experience more enjoyable, however there does not appear to be any difference in the frequency or willingness of individuals to undertake sexual activity, nor any tendency to greater promiscuity attributable to the drug effects, rather than the rebellious social attitudes characterised both by drug use and "free love" in the 1960s. In the 1990s, drug use is no longer considered a deviant activity by large segments of the population, and among young adults experimentation with illicit drugs appear now to be the rule rather than the exception.